title: Umbilical cord vitamin D, ionized calcium and myocardial oxygen demand.
abstract: OBJECTIVE
  Systemic blood vitamin D and total calcium are correlates of birthweight and cardiovascular disease but whether umbilical cord blood vitamin D and ionized calcium are correlates of birthweight and cardiovascular function is not known. This cross-sectional study correlates umbilical cord vitamin D, ionized calcium and birthweight with the heart rate-systolic pressure product (RPP), an indicator of myocardial oxygen demand.
  
  
  METHODS
  Cord blood vitamin D and ionized calcium concentrations were compared for vitamin D normal (≥50 nM, 20 ng/mL) and vitamin D deficiency (<50 nM, 20 ng/mL) in normal weight (≥2500 g) and low birthweight (LBW, <2500 g) newborns. Heart rate and blood pressure were measured during postnatal transition and RPP was computed.
  
  
  RESULTS
  RPP was positively correlated with birthweight (r = +0.52, p < 0.001) and with cord ionized calcium level (r = +0.42, p < 0.01) in the normal and LBW newborns. RPP was positively correlated with cord vitamin D level in the LBW newborns (raw r = +0.50, p < 0.05, normalized for birthweight r = +0.73, p < 0.01).
  
  
  CONCLUSIONS
  Small RPP, an indicator of low myocardial oxygen demand, in LBW newborns appears to correlate with low umbilical cord vitamin D and ionized calcium levels, suggestive of pathological heart development.
authors.affiliation: Division of Neonatology, Department of Obstetrics and Gynecology .
authors.forename: Inez
authors.initials: I
authors.lastname: Reeves
authors.forename: Willie
authors.initials: W
authors.lastname: Liang
authors.forename: M Sadegh
authors.initials: MS
authors.lastname: Asadi
authors.forename: Richard M
authors.initials: RM
authors.lastname: Millis
mesh_terms: D001724:Birth Weight / Q000502:physiology*; D001794:Blood Pressure; D002118:Calcium / Q000097:blood*; D003430:Cross-Sectional Studies; D005312:Fetal Blood / Q000378:metabolism*; D006321:Heart / Q000503:physiopathology; D006339:Heart Rate; D006801:Humans; D007230:Infant, Low Birth Weight / Q000097:blood / Q000502:physiology*; D007231:Infant, Newborn; D016014:Linear Models; D010101:Oxygen Consumption; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000175:diagnosis / Q000503:physiopathology*
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D; D002118:Calcium
keywords: Birthweight; rate-pressure product; umbilical cord blood; vitamin D deficiency